In order to improve the security of electronic apparatus, generally, a fingerprint identification device including a fingerprint detection circuit may be added to the electronic apparatus.
FIG. 1 shows a fingerprint detection circuit performing fingerprint detection by using a photodiode. As shown in the figure, the fingerprint detection circuit comprises a plurality of fingerprint detection circuits, each of which includes a photodiode D and a switch transistor T. An anode of the photodiode is connected to a low level input terminal, a cathode of the photodiode is connected to a first electrode of the switch transistor T, a gate of the switch transistor T is connected to a gate line, and a second electrode of the switch transistor T serves as an output terminal of the fingerprint detection circuit.
As shown in FIG. 2, the fingerprint detection circuit is provided in a layer A. When a finger 200 of an operator covers the fingerprint detection circuit of the fingerprint detection circuit, current passing through the photodiode may change, and the morphology of the fingerprint may be determined by detecting the change of the current of the photodiode.
However, in the above fingerprint detection circuit, when the finger of the operator covers the fingerprint detection circuit, difference between change of a photocurrent caused by a ridge of the fingerprint and that caused by a valley of the fingerprint is small. Therefore, it is impossible for the above fingerprint detection circuit to determine the morphology of the fingerprint accurately.